making a section of plywood to wrap around is not as difficult as you may think, but may also be a bear and a half depending upon the radius of the curve and the height of the fascia. The key is to not try and use plywood, but to make your own from thin layers of veneer and glue/clamp in a slightly tighter curve. If you are going to paint the fascia, then you can use materials that lend themselves well to bending like 1/8 in luan. If you are to stain it, then the outer laminate needs to be of the same material as the rest, but in 1/8 in. The key is to have solid bracing and clamps, glue it well and let it cure before removing the clamps.
Don't make it out of plywood, make it out of Masonite with plywood braces behind it.
If you absolutely HAVE to make it out of plywood, cut slots on the inside about 3/4 way through the plywood spaced about 1/2 in apart, that will let you bend the plywood.
Dave H. Painted side goes up. My website : wnbranch.com
I'm not familar with available lumber in Finland, but in the US, "bendable" plywood is available - usually on special order. This will allow bending down to a 16" or even smaller radius. That all said, unless you are going to stain, 1/8" tempered hardboard (Masonite in the US) is much easier to bend, and a lot cheaper. My
MAC... I used tempered hardboard ( masonite type product) and it worked both for my background panels and the facia.
Bob/IronGoat
Like Bob, I used 1/8" Masonite hardboard (non-tempered, though ) for the layout facia and to cove the corners (both inside and outside) of the backdrop. If the sheet is secured all along the vertical edges, the curve will be self-supporting and requires no other bracing.
Wayne